Hydro-cyclone separator



Dec. 19, 1967 R. s. CANTRELL HYDRO-CYCLONE SEPARATOR Filed July 21, 1964INVENTOR a n I. m mm mm/mao .7 s .017 w m. M f

United States Patent Ohio Filed July 21, 1964, Ser. No. 384,077 17Claims. (Cl. 209211) This invention relates to hydrocyclones separatinga flowing slurry or the like into accepted and rejected fractions, andparticularly to improvements therein achiev ing greater operatingefiiciency.

While not so limited, the invention has special reference tohydrocyclone separators, used in paper making processes to separateclean, usable fibrous material from a flowing slurry which, in additionto the usable material, contains unwanted heavier particles and dirt. Adevice of the kind described comprises means defining a separatingchamber circular in cross section and open at its opposite ends todefineoutlets for the respective fractions. Through an inlet at theaccepts end the flowing slurry is introduced tangentially into theseparating chamher in a manner to progress from one end to the other ina swirling helical motion. The open, accepts end is located to receiveand guide an inner vortex in which is comprised the accepted fraction,the rejected fraction discharging through the opposite or rejects end ofthe separating chamber. The described accepts and rejects ends of theseparating chamber are considered as providing for overflow andunderflow of respective slurry portions. These terms, however, do notdenote attitude limitations since the hydrocyclone can be mounted in anyposition which is convenient from an installation standpoint, the speedof movement of the slurry through the separator making the deviceoperationally independent of gravity.

In widespread, successful, use hydrocyclone separators as described arenevertheless the subject of continuing research and development lookingtoward increased operating efiiciency, that is, a more thorough andprecise separation between the acceptable and rejectable fractions. Ithas, in this connection, been observed that the average relativeefficiency of a cleaner increases with lowering slurry consistency.Also, it has been observed that efiiciency may be adversely affected bya tendency of slurry particles to orbit within the cleaner, inconditions of equilibrium brought about by counteracting hydraulic andcentrifugal forces.

The object of the invention is to simplify the construction as well asthe means and mode of operation of cyclonic separators, whereby suchseparators may not only be economically manufactured, but will be moreefficient and satisfactory in use, adaptable to a wide variety ofapplication, and be unlikely to get out of order.

Another object of the invention is to present a generally new method ofachieving more efiicient separation in a hydrocyclone.

A further object of the invention is to present a method and apparatusin hydrocyclonic separators wherein means are provided exerting adisturbing influence within the separating chamber.

Still another object of the invention is to introduce in hydrocycloneseparators a concept of use of an orbiting object which may be eitherfree or captive within the cleaner and which has an effect on theseparation process improving the efliciency thereof.

A further object of the invention is to provide a hydrocyclonicseparator possessing the advantageous structural features, the inherentmeritorious characteristics and the mode of operation herein mentioned.

With the above and other incidental objects in view as will more fullyappear in the specification, the invention intended to be protected byLetters Patent consists of the features of construction, the parts andcombinations thereof, and the mode of operation as hereinafter describedor illustrated in the accompanying drawings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviouslynot necessarily the only form of embodiment of the invention,

FIG. 1 is a view in longitudinal section, and partly diagrammatic, of ahydrocyclonic separator in accordance with a first illustrated form ofthe invention, showing flow disturbing means in the cleaner in the formof a free object.

FIG. 2 is a fragmentary view similar to FIG. 1 showing a secondillustrated form of the invention wherein the flow disturbing means isin the form of a captive object means.

FIG. 3 is a view in cross section of the object means as shown in FIG.1, FIG. 3 being enlarged relative to FIG. 1; and

FIG. 4 is a view similar to FIG. 3, showing a further form of theinvention utilizing a different arrangement for fixing the motion of theobject means.

Like parts are indicated by similar characters of reference throughoutthe several views.

In its illustrated embodiments, the invention is disclosed in ahydrocyclone separator as used especially in the pulp and paper industryto enable high standards of paper cleanliness. From a flowing pulpslurry containing not only the light fibrous material desirable forpaper making but also various undesirable materials, the unit operatesto separate the slurry into acceptable and rejectable fractions,directing these to respectively different outlets. According to theobjectives of the separator the highest possible percentage of barkspecks, dirt solids, fibre aggregates, shives and the like is excludedfrom the accepts outlet and directed as a part of the main slurry to therejects outlet.

Structurally a hydrocyclone separator according to the illustratedinventive forms comprises a shell having a unitary structure, as bybeing made of .a plurality of sections bolted or otherwise securedtogether. In FIG. 1 such a shell 10 includes a section 11 having theshape of a truncated cone, the interior of section 11 being hollow todefine a separating chamber 12 and the opposite ends of such chamberopening through the base and apex ends of the cone. Further comprised inthe shell 10 is a cylindrical section 13 on the base end of conicalsection 11 and in superposed aligned relation thereto. A back wall 14 ofsection 13 closes what may be considered the head of the device, exceptfor the installation therein of a tubular nozzle 15. The latter isconcentrically disposed in the shell 10 and projects through and beyondthe wall 14 at its opposite ends. The nozzle 15 thus has an outer endprojecting outside the shell 10 and an inner end within the shell, theenclosed portion of the nozzle extending some distance within the shell.The nozzle 15 is open at its ends for a free flow therethrough whilewithin the shell it occupies a position in spaced concentric relation tothe walls of shell 10.

At a point intermediate the inner end of the nozzle 15 and back wall 14there further is formed in section 13 an inlet 16 communicating througha laterally projecting boss 17 with the exterior of the shell, the boss17 being adapted to be connected in a system to supply thereto a pulpslurry under pressure. The arrangement is one to introduce the pulpslurry into the shell 10 tangentially of the walls thereof, thecontinued application of pressure at the inlet causing the pulp slurryto progress from the base end of the device toward the apex end in aswirling helical motion inducing centrifugal forces.

As a result of these forces there is left in the axis of the device anarea of low pressure creating what may be considered to be an innervortex moving contra to the outer vortex, that is in a direction fromthe apex end to the base end. The nozzle serves in this connection as avortex finder, its inner end extending inwardly of the shell to receivethe inner vortex and to conduct it out of the shell, the outer end ofthe nozzle being adapted for connection in a suitable conduit to conductthe materials caught in the inner vortex to a subsequent process step.In accordance with the concept and mode of operation of the separator,relatively light and desirable fibres from the liquid pulp slurry aregathered up by the inner vortex and conducted out the base end of thedevice as the accepted fraction while the remainder of the slurry leavesthe device through the apex end thereof as the rejected fraction.

Considering further the flow effects taking place in the separator, thevelocity of flow of the slurry accelerates rapidly and uniformly as itencounters the decreasing diameter of conical section 11. Thecentrifugal action forcing heavier particles outward toward the wall ofthe separating chamber is greatly multiplied. At the same time, however,a reversely spiraling column is formed in the central region of theseparating chamber, at the axis of which is a liquid free core. Inoperation, the light desirable pulp particles transfer from the outervortex to the inner vortex and are directed thereby to and through theaccepts nozzle 15.

The device provides opposed components of fiow directed respectivelytoward the base and apex ends of the cleaner. A pressure differentialfrom the outer chamber wall toward the centerline or axis of the chamberproduces a movement of liquid in this direction, this being inconjunction with the downward component of liquid flow. Some dirtparticles moving toward the outer wall under centrifugal influence mayfind themselves balanced by the involved forces. As a result, theseparticles assume a position of equilibrium and go into a more or lessfixed orbit. Eventually, however, these particles leave their orbits andappear, unpredictably, in the accepts or the rejects fractions. Also,when the slurry is introduced into the cleaner the pulp and dirt beginto move to the outside of the separator wall. The population of solidsadjacent the chamber wall increases. As subsequent dirt particlesattempt to join or move through this population collisions occur. Somedirt particles thus may not reach the outer wall but instead be causedto intersect the inner vortex and come under the influence of thisstream. The increased consistency in the region of the separator wallthus has the effect of restricting outward motion of dirt particles,allowing some of these particles to be drawn into the center vortexalong with acceptable material. Pulp material is separated or cleaned instages and improvements in the efficiency of the hydrocyclone aredesirable as reducing the number of required stages, as well asproviding clean, conditioned pulp for the paper making process in asfacile and economical a manner as.

possible.

In accordance with the instant invention improved efficiency is achievedby purposefully introducing into the separating chamber a flow disturberhaving the effect of reducing consistency at the separator wall and ofinhibiting orbiting by dirt particles. This is, in the illustratedinvention, an orbiting, physical object. Thus, and as shown in FIG. 1,an object .18 is in the separator shell 10. Caused by generated forceswithin the separating chamber to revolve in an orbital path therein,object 18 disturbs the equilibrium area conducive to orbiting of dirtparticles and accordingly inhibits such orbiting tendency thereby. Also,the circling motion of the object restrains the tendency of pulpparticles to assume dense relatively impenetrable formations. Theconsistency toward and in the region of the separator wall isaccordingly inhibited from increasing or is relatively reduced as beforedescribed.

The object 18 may assume various structural forms. It is, in theinstance of FIGS. 1 and 3 a hollow sphere made of a light weight plasticmaterial and perforated for flow of the slurry therethrough. The objectis thus responsive to centrifugal forces but is relatively unresponsiveto pressure exerted by the rejects flow toward the apex end of thecleaner. It readily assumes, therefore, an orbiting position, in theoperation of the hydrocyclone, at a point intermediate the accepts andrejects ends of the separator chamber. With the hydrocyclone at rest theobject may occupy a position seated in a relatively smaller diameterportion of the separating chamber. Under operating pressures, however,the object is lifted from its resting position and placed into orbit,the holes in the object allowing the slurry to pass through and out theobject.

The object has a size exceeding in diameter the nozzle 15 and the apexend of the hydrocyclone. While it may have a balanced construction itmay also be eccentrically weighted, as for example as shown in FIG. 3wherein a larger mass of material is located at point 19. Soeccentrically weighted the object tends to slide along the wall of theseparating chamber thus giving what is thought to be a more predictablebehavior pattern. It is not considered, however, that the invention islimited to the use of an object of any particular structural or balancecharacteristics. The invention .comprehends use of any physical meanspurposefully introduced into the separating chamber to accomplish by itsorbiting action of noted efiiciency improvements.

The object means 18 of FIG. 1 is a free object in the sense that it isunconnected to any part of the hydrocyclone. It is at liberty to findand assume its own position of equilibrium within the separating chamberand its orbital path may be at any location in a longitudinal sensetherein. In another aspect of the invention, however, captive objectmeans may be used, which means has a fixed orbital path, that is, fixedas to a certain height or endwise position in the cleaner. One form ofcaptive object apparatus is shown in FIG. 2. As shown therein, ahydrocyclone shell 21 is constructed like the shell 10 of FIG. 1. It hasinlet means 22 for the pulp slurry and a conical section 23 defining aseparating chamber 24. In the present instance, however, an acceptsnozzle 25 installed in the base end of the hydrocyclone has on its innerend two spaced apart collars 26 and 27. Interposed between these andfreely rotatable on nozzle 25 is a slip ring or bearing 28. Installed inthe periphery of the latter are the one ends of rods 29 and 31 having attheir opposite ends object means in the form of spheres 32 and 33respectively. The rods 29 and 31 project a short distance radially ofthe slip ring 28 and are then bent in the direction of the apex end ofthe cleaner shell to lie beyond the inner end of nozzle 25 inlongitudinal planes parallel to the shell axis. Accordingly, the spheres32 and 33 at the ends of the rods 29 and 31 are in a projected relationto the inner end of nozzle 25 while being disposed in the path of fiowof the helically moving slurry in such manner as to cause the assemblycomprising the spheres 32-33 rods 29 and 31 and ring 28 to rotate withthe slurry.

The spheres turn ina fixed lateral orbit and affect the pattern of flowsubstantially in the manner of the free object discussed in connectionwith FIG. 1. The objects 32 and 33 may be structurally characterizedlike the object of FIG. 1 or given any other structural embodiment foundsuitable to their purpose. In the illustrated instance two diametricallyopposed spheres are shown. A captive apparatus according to the conceptof FIG. 2 may comprise a single sphere, however, or the number andarrangement may be otherwise varied. Also, while the spheres areshown ina common transverse plane they may if desired be longitudinally offsetto revolve in different orbital paths.

The apparatus of FIG. 4 is similar to that of FIG. 2 in illustratingcaptive object means. As in the instances of FIGS. 1 and 2, hydrocyclonein accordance with the ems bodiment of FIG. 4 comprises a shell 34having a conical section 35 defining a separating chamber 36. Inletmeans 37 introduces the pulp slurry tangentially, setting up counterflowing vortices asbefore described. A nozzle 38 is installed in thebase end of the shell as a finder for the inner vortex. At the inner endof the nozzle 38 is installed a cross pin 39 which intermediate its endsis formed with a seat 41 and a through opening 42. A ball 43 is seatedin the recess 41 and a rod or other connector 44 is attached thereto andextends through opening 42 to a point substantially beyond the inner endof nozzle 38, the outer end of the connector being attached to a sphere45. The arrangement is thus one to suspend the sphere 45 from the nozzle38 with the sphere being free to move in an orbital path in response toflow of slurry through the cleaner but constrained to occupy a fixedorbit. The object 45 may be structurally characterized like the objects18 and 32 33 and performs a like function.

The accepts or overflow nozzle may be adapted to inhibit access theretoof dirt rich slurry portions under the influence of eddy currents in theforming outer vortex. In FIG. 2 the parts 26-2748 deflect such currentsaway from the nozzle inlet. In FIG. 4 a similar result is obtained byforming the nozzle exterior with an angularly sloping surface 46.

The object means of the invention has been described as operating toimprove the efficiency of a hydrocyclone by inhibiting particlesorbiting therein and by reducing consistency toward the separator wall.It is possible, however, that other operational factors are involvedpresently unknown. Thus no attempt is made exhaustively to analyze theeffects of the orbiting objects. It is known that efliciencyimprovements results and it has been the object herein merely to definesome of the likely or probable causes therefor without excluding others.

In the case of a free object, such object is preferably spherical,hollow, perforated and eccentrically weighted. Some of these factors areof less importance in the instance of a captive object. For example, thespheres 32-33 and 45 may be made of an inert solid such as plexiglass. Asuspension arrangement as shown in FIG. 2. substantially obviates a needfor eccentrically weighting, although this principle may advantageouslybe used in the form of FIG. 4, particularly if the connection 44 is aflexible one. The invention contemplates both a rigid and a flexibleconnection. A solid sphere may be eccentrically weighted in various waysas by drilling a hole from the surface of the sphere to the centerthereof. This moves the center of gravity of the sphere in the directionin which the hole is drilled.

From the above description it will be apparent that there is thusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is susceptible :of modification in its form, proportions,detail construction and arrangement of parts without departing from theprinciple involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has beendescribed in language more or less specific as to structural features,it is to be understood that the invention is not limited to the specificfeatures shown, but that the means and construction herein disclosedcomprise but one of several modes of putting the invention into effect,and the invention is therefore claimed in any of its forms ormodifications within the legitimate and valid scope of the appendedclaims.

I claim:

1. In a hydrocyclone operating to separate an acceptable fraction from aslurry containing acceptable and rejectable fractions, said hydrocyclonehaving oppositely disposed accepts and rejects outlets and inlet meansadmitting slurry in a manner to induce helical flow within thehydrocyclone; an object foreign to both fractions and unable todischarge with either purposefully introduced 6 into said hydrocycloneand characterized by means respending to a slurry in-fiow to cause saidobject to orbit in said hydrocyclone around said liquid free core, inthe area between said outlets, for increased separating efliciency.

2. Apparatus according to claim 1, wherein the object is free to assumeits own equilibrium position within the hydrocyclone, said last namedmeans residing in the structure of the object which is a perforatehollow article and physically unconnected to any part of thehydrocyclone.

3. Apparatus according to claim 2, wherein the object is formed as aneccentrically weighted hollow body having a dimension too large to allowit to pass through either said accepts or rejects outlet.

4. Apparatus according to claim 1, wherein the object is constrained tofollowed a fixed orbit, said last named means comprising elongate meanshaving a lateral dimension substantially less than that of said objectto suspend said object from one end of the hydrocyclone while it orbitsbetween said outlet.

5. In a hydrocyclone operating to separate an acceptable fraction from aslurry containing acceptable and rejectable fractions, said hydrocyclonehaving oppositely disposed accepts and rejects ends and inlet meansadmitting slurry in a tangential fashion near said accepts end forhelical flow toward said rejects end, a reverse vortex forming in thecenter of such flow and discharging through said accepts end; an objectforeign to both fractions and of a size too large to pass through eitherof said ends received in said hydrocyclone and orbiting therein saidhelical flow about said center vortex and inhibiting orbiting anddensity increasing tendencies of particles in said flow, said objectbeing of a hollow, light weight construction having openings for passageof slurry therethrough and physically unconnected to any other part ofthe hydrocyclone.

6. A hydrocyclone providing a separating chamber circular in crosssection, a tangential inlet for admitting a slurry containing acceptableand rejectable fractions with opposite ends of said chamber providingoutlets for respective fractions, a nozzle installed in the accepts endto project into said chamber and define a vortex finder for theacceptable fraction, said hydrocyclone being free of any interferingstructure along the axis thereof between said nozzle and rejectablefraction outlet whereby a liquid free core is formed along said axis andobject means suspended from said nozzle within the chamber to occupy aposition between said nozzle and the rejects end of said chamber tofollow an orbital path around said liquid free core therein inhibitingorbiting and density increasing tendencies of slurry particles.

7. A hydrocyclone according to claim 6, characterized by a slip ringrotatably mounted on said nozzle and suspending said object means.

8. A hydrocyclone according to claim 6, characterized by said objectmeans comprising hollow ball means and anti-friction bearing means onsaid nozzle mounting suspension means for said ball means.

9. A method of improving the efliciency of hydrocyclone separators whichoperate to remove an acceptable fraction from a flowing slurrycontaining acceptable and rejectable fractions, including the step ofpurposefully disturbing the normal pattern of flow of slurry through theseparator by orbiting in a transverse plane thereof object means whichoperate in a manner to inhibit orbiting and density increasingtendencies of slurry particles.

10. A hydrocyclone for separating light acceptable fibres from a flowingpulp slurry, including a conical section through which the slurry isswirled in a helical path from the base end toward the apex end, anaccepts outlet centrally positioned in the base end for discharge of theaccepted fraction, the apex end having an outlet for discharge of therejected fraction said hydrocyclone being free of any interferingstructure along the axis thereof between said outlets whereby a liquidfree core is formed along said axis, and flow disturbing means in theform of a body foreign to both fractions revolving in a transverseorbital path adjacent to the Wall of said conical section around saidliquid free core intermediate said accepts outlet and said apex end.

11. A hydrocyclone according to claim 10', characterized by meanssuspending the flow disturbing body from the base end of thehydrocyclone, said suspending means being long and slender relative tosaid body.

12. A method of improving the efficiency of hydrocyclone separatorswhich operate to remove an acceptable fraction from a flowing slurrycontaining acceptable and rejectable fractions, said fractions beingdischarged at respective opposite ends of the separator, including thesteps of admitting a flowing slurry into the hydrocyclone separator,purposefully introducing into said separator an object foreign to bothfractions, rendering the object unable to discharge with eitherfraction, and of causing said object to orbit in said separator in aplane between the ends thereof in a manner to inhibit orbiting anddensity increasing tendencies of slurry particles.

13. A method according to claim 12, characterized in that said step ofcausing said object to orbit in said separator is in part a function ofthe manner of admitting the flowing slurry into the hydrocyclone, theslurry being admitted tangentially therein and flowing in a helical pathto define a normal pattern of flow wherein a rejected fraction of solidsin the slurry moves in a longitudinal sense toward the rejects end ofthe separator While an accepted fraction of solids moves inwardly toward the center of the hydrocyclone and discharges through an acceptsend oppositely disposed relative to said rejects end, and further is afunction of the structural characteristics of said object which is afree body of susbstantial mass relative to the solids comprised ineither fraction and tending thereby to assume a position of equilibriumin the separator orbiting with the slurry in a plane between saidaccepts and rejects ends.

14. A method according to claim 12, wherein said step of rendering theobject unable to discharge with either fraction is accomplished bylimiting endwise movement of the object substantially to confine it tomotion in said plane.

15. A hydrocyclone for separating light acceptable fibres from a flowingpulp slurry, including a conical section defining a separator chamberthrough which the slurry is swirled in a helical path from the base endtoward the apex end, an accepts outlet positioned centrally of the baseend, said slurry containing unwanted rejectable solids and the apex endhaving an outlet for discharge of a rejected fraction comprising saidrejectable solids, a free body foreign to both said fractions in saidseparator chamber unconnected to any part of the hydrocyclone, and saidbody being characterized by means causing said body to revolve in atransverse orbital path adjacent to the wall of said conical sectionintermediate said accepts outlet and said apex end and to constituteflow disturbing means for increased separating efficiency.

16. A hydrocyclone according to claim 15, characterized in thatsaid freebody is eccentrically weighted for sliding motion along said wall.

17. In a hydrocyclone operating to separate an acceptable fraction froma slurry containing acceptable and rejectable fractions, saidhydrocyclone having oppositely disposed accepts and rejects ends andinlet means admitting slurry in a manner to induce helical flow withinthe hydrocyclone; an object foreign to both fractions and unable todischarge with either purposefully introduced into said hydrocyclone andcharacterized by means responding to a slurry in-flow to cause saidobject to orbit in said hydrocyclone, in the area between said ends, forincreased separating efficiency, the object being formed as a perforatedhollow sphere having a diameter too large to allow it to dischargethrough either the accepts or the rejects end.

References Cited UNITED STATES PATENTS 435,057 8/1890 Farrar -4151,909,184 5/1933 Lissman 55-300 2,153,270 4/1939 Osgood 55-42982,996,187 8/ 1961 Payne 209 -211 3,098,036 7/1963 Neumann 209144 FRANKW. LUTTER, Primary Examiner.

1. IN A HYDROCYCLONE OPERATING TO SEPARATE AN ACCEPTABLE FRACTION FROM ASLURRY CONTAINING ACCEPTABLE AND REJECTABLE FRACTIONS, SAID HYDROCYCLONEHAVING OPPOSITELY DISPOSED ACCEPTS AND REJECTS OUTLETS AND INLET MEANSADMITTING SLURRY IN A MANNER TO INDUCE HELICAL FLOW WITHIN THEHYDROCYCLONE; AN OBJECT FOREIGN TO BOTH FRACTIONS AND UNABLE TODISCHARGE WITH EITHER PURPOSEFULLY INTRODUCED INTO SAID HYDROCYCLONE ANDCHARACTERIZED BY MEANS RESPONDING TO A SLURRY IN-FLOW TO CAUSE SAIDOBJECT TO ORBIT IN SAID HYDROCYCLONE AROUND SAID LIQUID FREE CORE, INTHE AREA BETWEEN SAID OUTLETS, FOR INCREASED SEPARATING EFFICIENCY.